A mid-tone gray pattern with some cement looking texture.
Source Hendrik Lammers
Prismatic Curved Diamond Pattern 3 No Background
Source GDJ
To get the tile this is based on select the rectangle in Inkscape and use shift-alt-i
Source Firkin
Prismatic Triangular Seamless Pattern III With Background
Source GDJ
Abstract Arbitrary Geometric Background derived from an image on Pixabay.
Source GDJ
Colour version of the original pattern.
Source Firkin
A very dark spotted twinkle pattern for your twinkle needs.
Source Badhon Ebrahim
Background Wall, Art Abstract, Block Well & CC0 texture.
Source Ractapopulous
Seamless Prismatic Quadrilateral Line Art Pattern No Background
Source GDJ
A free background image with a seamless texture of cardboard. This texture of cardboard looks quite realistic, especially when is actually tiled.
Source V. Hartikainen
A re-make of the Gradient Squares pattern.
Source Dimitar Karaytchev
A nice and simple gray stucco material. Great on its own, or as a base for a new pattern.
Source Bartosz Kaszubowski
CC0 and a seamless pattern from a tile drawn in Paint.net .
Source SliverKnight
A seamless pattern with green and yellow diagonal lines on top of a white dotted background.
Source V. Hartikainen
Because I love dark patterns, here is Brushed Alum in a dark coating.
Source Tim Ward
This background has abstract texture with some similarities to wood.
Source V. Hartikainen
Prismatic Rounded Squares Grid 4 No Background
Source GDJ
Prismatic Groovy Concentric Background 4
Source GDJ
A seamless texture traced from an image on opengameart.org shared by Scouser.
Source Firkin
Zero CC tileable Crackled Cement (streaks) texture, photographed and made by me. CC0
Source Sojan Janso
Prismatic Hexagonalist Pattern No Background
Source GDJ